DR. KATZ: Trillions of germs cooperate with us

Dr. David Katz

Published 12:00 am, Sunday, June 24, 2012

Within our own skin, bacteria outnumber our cells by 10 to 1 at least. The population of the so-called microbiome totals roughly 90 trillion.

These germs -- although they are a vital part of us, they are, in fact, germs -- contribute to a wide array of critical body functions. Their importance has turned them into New Age media stars as well, with coverage A-list celebrities might envy. These bugs are big news.

Long known, though ever better studied, is the profound contribution of intestinal organisms to digestion. There is a growing body of evidence to suggest that disruptions to the normal flora of our GI tract may be implicated in a wide array of gastrointestinal disorders, and may be of particular importance in irritable bowel syndrome. There is a corresponding body of evidence, fast growing, that replenishing normal flora with probiotic supplements may be beneficial in such circumstances.

There is growing recognition that disruptions in gastrointestinal flora may be a factor or, in unusual but not truly rare cases of weight-loss resistance, perhaps even the factor conspiring to cause obesity. There is some early evidence that reconstituting intestinal flora through the easy expediency of probiotic supplements -- or the more dramatic and perhaps regrettably if aptly named "fecal transplant" - may be quite helpful in such circumstances.

And there is growing awareness as well that our resident microbes influence almost every aspect of our physiology, from hormonal balance to metabolic rate to immune system function and inflammation.

I believe these bugs tell us more about ourselves than how inescapably germy we are.

In his characteristically articulate, compelling, and well-researched book, "Outliers," Malcolm Gladwell builds a new podium for John Donne's time-honored admonition: "No man is an island." Gladwell demonstrates that the examples of "self made" people our society most reveres are in fact products of both aptitude and opportunity, circumstance and communal support.

The salient public health threats of our time are a wide array of social and environmental factors that in the aggregate contrive to make obesity, diabetes, and other chronic disease epidemic. Lifestyle factors each of us potentially controls every day constitute the master levers of medical destiny, exerting greater influence on years in life and life in years than anything else. But these lifestyle factors are in turn much influenced by the modern environment in which we live and, collectively, devised.

Against this backdrop, we have gravitated to the poles of ideology.

Some invoke personal responsibility, as if lifting oneself up by the bootstraps is fully independent of all other influences, including, presumably, the existence of a boot maker. Others argue for environmental reform, as if we are entirely helpless while waiting on the world to change.

A middle path would concede that we like to be autonomous, and sometimes have the stuff to be so but often don't, and are never entirely apart from the influence of others. An approach informed by biology would see an opportunity for common ground somewhere between "get there alone or die trying" and running a hammer and sickle up the flagpole.

The human body is, quite simply, not viable without the biological body politic. With that as precedent and precautionary tale, perhaps society can acknowledge the same exigency, and accept that some challenges are best -- or even only -- addressed communally.

Autonomy matters. Personal responsibility matters. We often can, and as often should, take matters of moment into our own hands. We often can, and as often should, be masters of our fate, and captains of our souls.

But we should nonetheless acknowledge that the best defenses of the human body reside largely, inextricably with the body politic. Public health is for the public, and is best advanced by the collective efforts of the public.

In society, as in our own skin, from Gladwell's outliers of sociology to the gastrointestinal microbes of biology, we are never, ever alone.